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NCT07373301

PHASE2

Phase IIa/b Trial of PvCS/Montanide ISA-51 Malaria Vaccine in Adults in Chocó, Colombia

Sponsor: Malaria Vaccine and Drug Development Center

View on ClinicalTrials.gov

Summary

This clinical study will evaluate an investigational malaria vaccine called PvCS/Montanide ISA-51 to determine whether it is safe and whether it can protect adults from infection with Plasmodium vivax, one of the main parasites that causes malaria. P. vivax malaria is common in tropical regions, including Colombia, and can lead to recurrent fever, anemia, and prolonged illness. Currently, no licensed vaccine effectively prevents P. vivax infection. The investigational vaccine (PvCS) contains synthetic peptides derived from the circumsporozoite (CS) protein located on the surface of P. vivax sporozoites. The vaccine is formulated with the adjuvant Montanide ISA-51 to enhance the immune response. This study aims to assess the safety of the PvCS/Montanide ISA-51 formulation and to determine whether it can prevent malaria after controlled exposure to the parasite. This is a Phase IIa/b, randomized, double-blind, placebo-controlled clinical trial conducted by the Malaria Vaccine and Drug Development Center (MVDC/CIV) in collaboration with ASOCLINIC IPS and the Pacific Health Institute (INSALPA) in Quibdó, Chocó, Colombia. A total of 72 healthy adults aged 18-50 years from malaria-endemic areas will participate. Participants will be randomly assigned in a 2:1 ratio to receive either the PvCS/Montanide ISA-51 vaccine or a placebo. The study product will be administered by intramuscular injection at months 0, 2, and 4. After each vaccination, participants will be monitored for side effects and provide blood samples to measure immune responses, including antibody levels and T-cell activity. Approximately one month after the third vaccination, participants will undergo a controlled human malaria infection (CHMI), during which they will be exposed to P. vivax through the bite of infected mosquitoes under strict medical supervision. Following exposure, participants will be monitored daily using blood tests to detect malaria at the earliest stage. If malaria parasites are detected-or if 21 days pass without infection-participants will receive prompt, effective antimalarial treatment based on Colombian national guidelines. All participants will continue to be followed for up to 12 months after the challenge to ensure safety and assess long-term outcomes. Primary goals of the study include: Determining whether the PvCS/Montanide ISA-51 vaccine prevents P. vivax infection after CHMI. Measuring the time between exposure and first detection of parasites (pre-patent period). Evaluating the safety and tolerability of the vaccine. Secondary goals include: Measuring immune responses generated by the vaccine. Exploring relationships between immune responses and protection from infection. The total duration of the study is expected to be approximately 30 months, including recruitment, immunizations, challenge procedures, and follow-up. Results will help determine whether this vaccine can safely protect adults against P. vivax malaria and guide planning for future larger-scale vaccine trials in endemic populations.

Official title: Determination of the Protective Efficacy of the PvCS/Montanide ISA-51 Vaccine Formulation Against Controlled Infection With Plasmodium Vivax Sporozoites

Key Details

Gender

All

Age Range

18 Years - 50 Years

Study Type

INTERVENTIONAL

Enrollment

Start Date

2026-01-19

Completion Date

2028-06-12

Last Updated

2026-01-28

Healthy Volunteers

Yes

Conditions

Plasmodium Vivax Malaria Plasmodium Vivax Infection Malaria Prevention

Interventions

BIOLOGICAL

PvCS/Montanide ISA-51 VG Vaccine

The vaccine contains a synthetic peptide representing the central repeat and flanking regions of the Plasmodium vivax circumsporozoite (CS) protein, formulated with Montanide ISA-51 VG (Vaccine Grade), a water-in-oil adjuvant that enhances both antibody and T-cell responses. This formulation is distinct from other malaria vaccine candidates because it specifically targets P. vivax using a synthetic CS peptide antigen, rather than a recombinant protein or viral vector platform. Each 0.5-mL dose is administered intramuscularly in the deltoid at 0, 2, and 4 months. Participants will be closely monitored for safety, reactogenicity, and immunogenicity after each vaccination. Approximately one month after the final dose, volunteers will undergo a controlled human malaria infection (CHMI) via exposure to Anopheles albimanus mosquitoes infected with P. vivax sporozoites to assess protective efficacy.

BIOLOGICAL

Placebo - Montanide ISA-51 VG Adjuvant Alone

The placebo consists of Montanide ISA-51 VG (Vaccine Grade) adjuvant without the Plasmodium vivax circumsporozoite (CS) peptide antigen. It is a sterile water-in-oil emulsion prepared and administered in the same manner as the investigational vaccine to maintain blinding. Each 0.5-mL dose is given intramuscularly in the deltoid at 0, 2, and 4 months. The placebo is visually indistinguishable from the vaccine and follows identical handling, storage, and administration procedures. Participants in the placebo group will undergo the same safety monitoring, blood sampling, and controlled human malaria infection (CHMI) one month after the final dose to allow direct comparison of efficacy, safety, and immune responses.

Inclusion Criteria Age 18-50 years, male or female. Healthy adults, as determined by medical history, physical examination, and screening laboratory tests. Able and willing to provide written informed consent prior to any study procedure. Available for the full duration of the study, including follow-up through 12 months post-challenge. Group-specific criteria: Malaria-naïve cohort: No prior malaria infection or residence in malaria-endemic areas; negative malaria serology at screening. Semi-immune cohort: Residence ≥ 5 years in a P. vivax-endemic area and documented or self-reported prior malaria exposure. Screening negative for HIV, hepatitis B surface antigen (HBsAg), and hepatitis C virus antibodies. For women of childbearing potential: Negative pregnancy test at screening and prior to each vaccination and/or CHMI. Commitment to use effective contraception (hormonal, IUD, barrier methods, or abstinence) from screening through the end of follow-up. Willingness to comply with all study procedures, including repeated blood sampling, controlled human malaria infection (CHMI), and inpatient or outpatient monitoring as required. Exclusion Criteria Previous participation in any malaria vaccine clinical trial or any controlled human malaria infection (CHMI) study. History of severe allergic reactions, including anaphylaxis, to vaccines or vaccine components such as Montanide ISA-51 VG, adjuvants, or synthetic peptides. Clinically significant acute or chronic medical conditions that may increase risk or interfere with study participation, including but not limited to: Cardiovascular disease Hepatic or renal impairment Neurological or psychiatric disorders Autoimmune diseases Hematologic abnormalities Immunodeficiency or immunosuppressive conditions Use of immunosuppressive therapies, systemic corticosteroids, antimalarial medications, or other agents that may interfere with vaccine immune responses within 30 days prior to enrollment. Receipt of immunoglobulins or blood products within 3 months prior to screening. Pregnancy or breastfeeding at screening or planned pregnancy during the study period. Participation in another clinical trial of an investigational product or device within 30 days prior to enrollment or planned participation during the study. Any clinically significant abnormality on screening laboratories, ECG, or physical examination that, in the investigator's judgment, could: Pose a safety risk, Confound study results, or Impair adherence to study procedures. Any condition or circumstance that, in the investigator's opinion, could compromise volunteer safety or the integrity of the trial.

Locations (1)

Malaria Vaccine and Drug Development Center (MVDC)

Cali, Valle del Cauca Department, Colombia